The present invention relates generally to keyboards, and more particularly a keyboard attached to a laptop personal computer (“PC”), a personal digital assistant (“PDA”), and other portable electronic apparatuses.
Along with the recent development and spread of the laptop PCs, small and low-profile bodies convenient for portability have been increasingly demanded. In addition, laptop PCs with a low-profile body have been demanded to detect keying-in with precision and to provide ergonomically good operability.
For the low-profile laptop PC, a method for thinning a keyboard has been investigated. For example, Japanese Laid-Open Patent Application No. 11-213806 proposes a key moving mechanism, which is also referred to as a pantograph mechanism. Here, FIG. 6 is a schematic partial sectional view of a conventional key moving mechanism. A moving mechanism 510 shown in FIG. 6 includes a linkage that crosses like an X-shape. When a key 502a is pressed down, the moving mechanism 510 deforms around a rotary part 512 and slides through slide parts 514. Then, a contact 504a in a rubber member 504 contacts switch parts 518 on a base 516, and transmits keying information to a substrate (not shown). FIG. 7 shows a schematic partial sectional view of another conventional keyboard structure disclosed in Japanese Laid-Open Patent Application No. 2001-597651. Here, FIG. 7 is a schematic partial sectional view of another conventional key moving mechanism. The moving mechanism 620 shown in FIG. 7 is a V-shaped linkage referred to as a gear linkage, in which when a key 602b is pressed down, a moving mechanism 620 rotatably attached to a rotary part 623 engages with a gear part 624 and slides through slide parts 622. Accordingly, a contact 604b in a rubber member 604 contacts a switch part 628 on a membrane 630 and transmits press information to a base (not shown).
The conventional moving mechanisms shown in FIGS. 6 and 7 ascend and descend the key in a vertical direction, and thus are unsuitable for the low-profile body. This is because a user ergonomically feels uncomfortable unless a keystroke as a distance by which the key top travels (KS in FIGS. 6 and 7) is equal to or larger than the predetermined distance, and this predetermined distance hinders the low-profile body.
On the contrary, Japanese Laid-Open Patent Application No. 2000-348562 discloses a moving mechanism for descending and ascending the key in an oblique direction, rather than the vertical direction. The moving mechanism in this reference shortens the vertical length convenient for low-profile body while moving the key in the oblique direction so as to maintain the long keystroke. However, the moving mechanism may disadvantageously incline the key top in moving the key, consequently causing contact failure between the contact and switch part and resultant recognition failure of keying. The inclined, moving key top also makes a user uncomfortable.